Does the severity of angina affect the results of treatment?

This study investigated whether the severity of chest pain (angina) affects the impact of different treatments for stable coronary artery disease (CAD) in people with type 2 diabetes (T2D). It was determined that those with more severe angina were more likely to need revascularization (PCI or CABG), and to have severe angina after treatment. Additionally, CABG was found to be the best treatment to reduce the risk of cardiac events, revascularization, and severity of angina after treatment, regardless of severity of angina before treatment. 

People with CAD have narrow or blocked arteries in the heart, which increases the risk of a heart attack. There are many different treatment options for people with stable CAD. Optimal medical therapy (OMT) for stable CAD includes treatment with drugs that prevent blood clots and lower cholesterol. PCI (or angioplasty) is a non-surgical procedure where narrow or blocked arteries are widened or unblocked. CABG is a surgical procedure where a healthy blood vessel is taken and connected (‘grafted’) to the blocked artery. This creates a ‘bypass’ around the blocked artery.

The goal of treatment is to reduce the risk of mortality and heart attacks, and to reduce angina severity. Often those with mild angina receive OMT, and those with more severe angina receive PCI or CABG. However, the influence of angina severity on the impact of these different treatments is still under investigation. This is especially important in people with T2D, who may have less severe symptoms, but more narrow arteries. 

This study examined the results of 3 different studies. 5,027 patients with stable CAD and T2D took part. They were randomly divided into 3 groups. One group received OMT only. The second group received PCI and OMT. The third group received CABG and OMT. They were followed for 5 years.

In all groups, the more severe angina was before treatment, the more likely they were to need revascularization. Revascularization means another PCI or CABG, or a first PCI or CABG in the OMT group. Those with the most severe angina were 81% more likely to need revascularization than those without symptoms of angina.

The CABG/OMT group was 64% less likely than the PCI/OMT group to need revascularization, regardless of initial angina severity. The CABG/OMT group was 76% less likely than the OMT group to need revascularization in all patients, but mainly those with more severe angina before treatment. The PCI/OMT group was 34% less likely than the OMT group to need revascularization, regardless of initial angina severity.

The CABG/OMT group was 29% less likely to experience a cardiac event than the PCI/OMT group, and 21% less likely than the OMT group. Cardiac events included deaths, heart attacks, and strokes. The OMT and PCI/OMT groups had similar risks of cardiac events. Severity of angina before treatment did not change the effects of different treatments on cardiac events.

Those with more severe angina before treatment were more likely to have more severe angina 1 year after treatment. The CABG/OMT group was 38% less likely than the PCI/OMT group, and 45% less likely than the OMT group, to have severe angina after 1 year. The benefits in the CABG group were mainly seen in those who had severe angina before treatment.

The study concluded that those with more severe angina were more likely to need revascularization, and to have severe angina after treatment. Furthermore, CABG was found to reduce the risk of cardiac events, revascularization, and severity of angina after treatment, more than PCI or OMT alone, regardless of severity of angina before treatment.

Differences between the different studies may have affected the results. The majority of participants were white and were men. Thus the results may not apply equally to all people with stable CAD and T2D. Additionally, this study was funded by a company that manufactures drugs to treat angina.

Discuss different treatment options for CAD with your physician.